Related Stories

A translation of old scientific papers has confirmed that the scientist who received a Nobel Prize for his work on cosmic rays wasn't alone in his discovery.

Austrian physicist Victor Hess received the Nobel Prize in 1936 for identifying the source of cosmic rays - high energy particles that stream into the atmosphere from space and the Sun.

Professor Alessandro De Angelis of the University of Udine in Italy and colleagues claim recently translated the works of twentieth century Italian Domenico Pacini, show he discovered the source two years earlier.

Cosmic rays have long puzzled physicists, and at the turn of the twentieth century most scientists thought they stemmed from radiation in the Earth's crust.

Their extraterrestrial origin was hypothesised, but it wasn't confirmed until 1912, when Hess dramatically ascended five kilometres into the atmosphere in a balloon equipped with an electroscope, used to measure electrostatic charge.

Because the electroscope showed that the discharge rate increased with altitude, Hess was able to conclude that cosmic rays couldn't originate from Earth.

Underwater

But it now appears Pacini, a professor at the University of Bari, Italy, had come to the same conclusion after submerging a similar device in the Bay of Livorno in Tuscany in 1910.

He found that when the device floated on the water, the oscilloscope showed that the level of ionising radiation was higher than would be expected away from the radioactive minerals in the soil.

Furthermore, when the device was submerged, the signal was weaker - indicating the water was absorbing radiation.

Pacini died in 1934, making him ineligible for the Nobel Prize, which is not awarded posthumously. De Angelis believes this contributed to the obscurity surrounding his discovery.

"Pacini was kind of more 'polite', because he quoted Hess while the contrary was often not true," says De Angelis.

Pacini also wrote his notes in Italian, and as a meteorologist and geologist, didn't have the academic background to "sell his results", he says, while Hess, a physicist, translated his original German publications into English after 1920.

"Since he did not get the Nobel, his work was somehow forgotten," De Angelis says.

Not forgotton

Science historian Dr Gerhard Wiesenfeldt of the University of Melbourne says while the relationship between the two scientists "requires study", Hess's argument was much clearer and his experiment was much stronger.

"Pacini does make worthwhile contributions, but I wouldn't call him the co-discoverer."

Wiesenfeldt says Pacini's work wasn't looked at closely because he wasn't a radio physicist.

"Pacini is a bit unlucky, but he's also not quite forgotten," he says.

A 1984 review by UK astronomer Royal Arnold Wolfendale, published in the journal Reports on Progress in Physics lists Pacini as first suggesting the non-radiogenic origin of the rays.

"In general science discoveries are much more complex than they are made out to be afterwards."